Please add a functionally "Open as root".
Just add a custom action for that, "gtksu thunar %d" for directories or something like that. For file managers there is no such thing as being root, and all problems implementing this, just use a frontend like sudo/gtksu etc.
But wouldn't it be possible to have such a function right in the context menu? e.g. /etc/foo.conf -> right click -> Open as root also using gksudo
Ahh sorry, you can ignore my previous post as I didn't understand you correctly (but now I do). -------------- (addressing your post:) Then couldn't you implement this this custom action as default - as is the case with "Open in a Terminal"? "Open as root" is actually needed quite often I think. Btw Windows Explorer also has a function "Open as Administrator".